A puffer type gas circuit breaker for electric power includes a container filled with an arc extinguishing gas and the container includes therein a fixed contact, a movable contact connected thereto and separated therefrom, a puffer cylinder connected to the movable contact, a piston moving relative to an inner wall surface of the puffer cylinder, a puffer room having a suction hole for sucking an arc extinguishing gas and an ejection hole for ejecting the gas toward the contact, and a wear ring provided on an outer circumferential portion of the piston and sliding on the inner wall surface of the puffer cylinder, and the arc extinguishing gas ejected from the ejection hole blows to an arc generated in an opening between the fixed contact and the movable contact so that the arc disappears.
In many cases, the puffer cylinder of the puffer type gas circuit breaker with such a configuration uses aluminum (pure aluminum or aluminum alloy) for a decrease in weight. However, since aluminum is a material that is easily abraded, various surface treatments may be applied thereto to prevent the abrasion of sliding portions.
In general, an alumite treatment, a plating treatment, or various coatings are adopted in order to improve the abrasion resistance of aluminum.
As a technology for improving the abrasion resistance of aluminum, for example, there is known a technology disclosed in PTL 1. PTL 1 discloses a technology in which a puffer cylinder, an operation rod, and a pressing plate are formed of pure aluminum or an aluminum alloy and an aluminum oxide film is formed by an alumite treatment at a portion where these components are in contact with each other.
Further, PTL 2 discloses a technology in which a seal rod is slidably supported by a penetration hole of a gas container and a coating layer of amorphous carbon or diamond-like carbon which is an abrasion resistant and low friction material is formed on a sliding surface sliding on the seal rod in a seal member formed of synthetic rubber or fluororesin to prevent an arc extinguishing gas inside the gas container from leaking to an operation mechanism.
Furthermore, PTL 3 discloses a technology in which a lubricating silicone grease is applied to an outer circumferential surface of a cylinder sliding when a fixed arc contact and a movable arc contact are opened and separated in order to reduce friction.